α-Olefins are important items of commerce, hundreds of millions of kilograms being manufactured yearly. They are useful as monomers for (co)polymerizations and as chemical intermediates for the manufacture of many other materials, for example detergents and surfactants. Presently most α-olefins are made by the catalyzed oligomerization of ethylene by various catalysts, especially certain nickel complexes or aluminum alkyls, see for instance U.S. Pat. No. 4,020,121 and I. Kroschwitz, et al., Ed., Kirk-Othmer Encyclopedia of Chemical Technology, 4th Ed., Vol. 17, John Wiley & Sons, New York, pp. 839–858. Depending on the catalyst used and the product distribution desired various processes are used, but they tend to operate at high pressures, and/or high temperatures, and/or have large recycle streams, and/or be complex (for example recycle of catalyst streams), all of which increases the capital cost of the manufacturing plant and/or increases plant operating costs, both of course undesirable. Therefore, better processes for making α-olefins are of commercial interest. Some of the processes which use these catalysts, especially alkylaluminum compound (alone) catalysts, are reported to utilize plug flow reactors.
Recently, as reported in U.S. Pat. No. 6,103,946, which is hereby incorporated by reference, it has been found that iron complexes of certain tridentate ligands of 2,6-pyridinecarboxaldehye(bisimines) or 2,6-diacylpyridine(bisimines) are excellent catalysts for the production of α-olefins from ethylene. U.S. Patent Application Publication 2002/0016521 describes a manufacturing process for α-olefins using these catalysts in which a liquid full continuous stirred tank reactor is used, optionally followed by a final reactor which may be plug flow reactor. The process described herein concerns a modified plug flow reactor.